title: Men with low vitamin A stores respond adequately to primary yellow fever and secondary tetanus toxoid vaccination.
abstract: Current recommendations for vitamin A intake and liver stores (0.07 micromol/g) are based on maintaining normal vision. Higher levels may be required for maintaining normal immune function. The objective of this study was to assess the relationship between total body vitamin A stores in adult men and measures of adaptive immune function. We conducted an 8-wk residential study among 36 healthy Bangladeshi men with low vitamin A stores. Subjects received a standard diet and were randomized in a double-blind fashion to receive vitamin A (240 mg) or placebo during wk 2 and 3. Subjects received Yellow Fever Virus (YFV) and tetanus toxoid (TT) vaccines during wk 5. Vitamin A stores were estimated by isotopic dilution during wk 8. Vaccine-specific lymphocyte proliferation, cytokine production, and serum antibody responses were evaluated before and after vaccination. Vitamin A supplementation increased YFV- and TT-specific lymphocyte proliferation and YFV-specific interleukin (IL)-5, IL-10, and tumor necrosis factor-alpha production but inhibited development of a TT-specific IL-10 response. Both groups developed protective antibody responses to both vaccines. Some responses correlated positively with vitamin A stores. These findings indicate that the currently recommended vitamin A intake is sufficient to sustain a protective response to YFV and TT vaccination. However, YFV-specific lymphocyte proliferation, some cytokine responses, and neutralizing antibody were positively associated with liver vitamin A stores > 0.084 micromol/g. Such increases may enhance vaccine protection but raise the question of whether immune-mediated chronic diseases may by exacerbated by high-level dietary vitamin A.
authors.affiliation: Program in International and Community Nutrition, Department of Nutrition, University of California Davis, CA 95616, USA.
authors.forename: Shaikh M
authors.initials: SM
authors.lastname: Ahmad
authors.forename: Marjorie J
authors.initials: MJ
authors.lastname: Haskell
authors.forename: Rubhana
authors.initials: R
authors.lastname: Raqib
authors.forename: Charles B
authors.initials: CB
authors.lastname: Stephensen
mesh_terms: D000328:Adult; D000914:Antibodies, Viral; D006801:Humans; D008099:Liver / Q000378:metabolism; D008297:Male; D013745:Tetanus Toxoid / Q000276:immunology*; D014801:Vitamin A / Q000276:immunology* / Q000378:metabolism; D022341:Yellow Fever Vaccine / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D013745:Tetanus Toxoid; D022341:Yellow Fever Vaccine; D014801:Vitamin A